Comparative assessment of prototype digester configuration for biogas recovery from anaerobic co-digestion of food waste and rain tree leaf as feedstock

• Prototype single-stage and two-stage anaerobic digesters for co-digestion of food waste and rain tree leaf were developed.
• Effects of mixing ratio of food waste and rain tree leaf and C/N ratio on the biogas production were investigated.
• Anaerobic co-digestion could achieve the highest CH4 yield by mixing food waste with rain tree leaf at the ratio of 95:5.
• Higher yield of biogas was obtained with the prototype two-stage anaerobic co-digestion system.
• At present, the biogas has been utilized for cooking as a model case study for high-rise building application.

A comparative assessment of the developed prototype single-stage and two-stage anaerobic digesters for biogas recovery from anaerobic co-digestion was performed using food waste and rain tree leaf as feed stock. Rain tree or Chamchuri tree is an important tree in Chulalongkorn university and it is recognized as the university symbol. Up to now, Chulalongkorn University has grown more than a hundred of rain trees in the campus. Thus, rain tree leaf is found to be the major gardening wastes. Continuous operation of two prototype systems was implemented to investigate biogas recovery potential. From the obtain results, it was found that higher percentage of organic carbon and total volatile solid reduction were obtained with the prototype two-stage anaerobic digester. Higher COD reduction percentage of 85.74% could be achieved with the prototype two-stage anaerobic digester. Moreover, a maximum biogas production of 0.834 m3/kg of organic waste-day was obtained with the prototype two-stage anaerobic digester at the C/N ratio of 21, while the prototype single-stage anaerobic digester achieved a maximum biogas production of 0.41 m3/kg of organic waste-day at the same C/N ratio of 21.